1. Field of the Invention
The present invention relates, in general, to lens arrays and devices for use in viewing or displaying images that are interlaced to display animated, three-dimensional (3D), and other images, and, more particularly, to lenticular devices, as well as products incorporating such lenticular devices and methods of fabricating such lenticular devices, that include a lens array or sheet of lenticular material combined with an interlaced image such that more than one lens or lenticule (or a lens set) is used to view or display each set of interlaced images that is repeated across the interlaced image.
2. Relevant Background
There is a continuing and growing demand for lenticular devices that can effectively provide elaborate graphics. This demand is due in part to the need for the retailers to separate their products from other products, and one effective technique is to enhance shelf appeal by including eye-catching imagery such as animation or a three-dimensional (3D) effect. For example, water bottles are presently sold with wrap-around labels that display images, and gift cards are sold at a large majority of retail stores that include animation or 3D images. Such imagery can be provided by using lenticular graphic labels to provide three-dimensional (3D) and animated imagery such as a short clip of a movie. Lenticular lens material is used in the packaging industry for creating promotional material with appealing graphics and typically involves producing a sheet of lenticular lens material, applying an image to the lens material, and adhesively attaching the lenticular lens material to a separately produced object for display.
In general, the production of lenticular devices such as gift cards and labels includes selecting a number of images such as sequential portions of a movie or animated clip to use to create a desired visual effect. Each of these images are sliced into a predefined number of slices or interlaces (such as 10 to 30 or more slices per image), and the slices of each image are interlaced to form an interlaced image made up of a large number of image sets or sets of interlaces. Lenticular lenses or lens sheets are then mapped to the interlaced image, and the lenticular lenses are fabricated according to this mapping such that each lenticular lens is paired with (or covers) one of the sets of interlaces. The lenticular material or lens sheet generally includes a transparent web that has a flat side or layer and a side with optical ridges and grooves formed by linear or elongated lenticules (i.e., lenses) arranged side-by-side with the lenticules or optical ridges extending parallel to each other over the length of the transparent web. To provide the unique visual effects, ink (e.g., four color ink) is applied to or printed directly on the flat side of the transparent web to form a thin ink layer or the image layer containing the sets of interlaces or image slices, which is then viewable through the transparent web of optical ridges.
Each lenticule or lens of the lenticule layer is paired or mapped to a fairly large set or number of the interlaced image slices or elements. For example, one lenticule may be paired with up to 10 to 30 or more interlaced image slices or interlaces depending on images (or frames of a movie clip or the like is used), and generally only one of the slices or interlaces is visible through the lenticule at a time based on the position of the lenticule relative to a viewer's eye. In other words, the animation, 3D, or other graphic effect is achieved by moving the lenticule or the viewer's position to sequentially view each of the interlaced image slices under the lenticule and allow a viewer to see each of the images or frames in the interlaced image or ink layer by combining the slices or interlaces viewed from all the lenticules.
In producing conventional lenticular lens material and lenticular devices, it is desirable to use as little material as possible, i.e., to produce effective lenticules or lenticular lens arrays or sheets with as thin as web material as possible. Decreasing lens thickness is also desirable to facilitate fabrication using techniques, such as web printing, that are very difficult or impractical with thicker lens materials. Thin lenticular lens material is desired to save on material costs and to provide a relatively flexible lens material or substrate that can be easily applied to products such as gift, smart, and credit cards, and product containers, such as in a label that can be attached to a box or to a bottle as part of a wraparound label or on a cup to provide desirable visual effects.
However, such shrinking of the lenticles has proven very difficult with limitations associated with printing the interlaced images often preventing the lens layer or web from being made very thin. As noted above, all the interlaced slices for each image set or set of interlaces are placed underneath a single lenticule such that numerous slices have to be printed with very little width to be mapped to the lenticles width or pitch. However, the printing can presently only be done with a limited degree of resolution. With coarser lens arrays (i.e., with lower frequency or lenses per inch (LPI)), the printing can be accomplished more easily and mapping to lenticules of the image slices achieved more accurately. However, coarser lens arrays with frequencies of 10 to 30 LPI tend to be very thick because general physics or optical rules for focusing with conventional lenticular material require that more lens thickness or more lens material be provided to achieve effective focusing. For example, a 15 LPI lenticular lens array with a fairly common viewing angle (such as a 22-degree viewing angle) may be mapped to an interlaced image that is printed or provided directly behind the lenticular lens array, with each of the lenticules in the lens array being mapped to or paired with all image slices of a paired segment of the interlaced image. If the lens array is formed from acrylic, the lens array would need to be about ⅜-inch thick to enable the lenticules to properly focus on the paired image slices. Conversely, the frequency of the lenticular lens array may be increased (i.e., a finer lens array may be used). However, existing limitations on printing have resulted in the thinnest lenticular lens arrays being at least about 8 to 120 mils thick, and the mapping accuracy required at these lower thicknesses and higher lenticule frequencies often results in lower quality imaging results and increased fabrication or printing costs.
FIG. 1 illustrates a conventional lenticular device 10 in common use for products such as gift cards and in labels. The lenticular device 10 includes a lens array or sheet 12 with lenticules or lenses 16 formed on one side. On an opposite planar side 14, an image layer or ink layer 20 is provided that includes a plurality of interlaces or image slices 22 that are provided with in image sets or sets of interlaces under each of the lenticules or lenses 16. The interlaces 22 correspond to an interlaced image that is made up of only three images or image frames in this simplified example, and using conventional mapping techniques, each image set or set of interlaces includes three interlaces (i.e., an interlace corresponding to each of the three images or image frames) provided under each lens 16.
The number of images or frames in the interlaced image is chosen such that the interlaced images are an integral multiple of the lenticular pitch and such that the entire image set or set of interlaces fits completely underneath a paired or mapped lenticule or lens. This insures that the same pattern of angular spread of images exists across the lenticular structure, which is shown in FIG. 1 where three interlaces corresponding to the first, second, and third image or image frame are placed under each lenticule 16 in a similar position such that the rays that exit the lens sheet or array are at the same angle (as shown by rays 30, 34, and 38 associated with these three images). In practice, there may be a small change in angular distribution of the rays 30, 34, 38 across the structure 10, but the rays essentially drift together in the usable zone presented to a viewer so that the structure 10 may have to be titled to see a desired effect such as motion, flash, or 3D.
While such conventional lenticular devices are useful, printing limitations associated with providing interlaces at small widths has proven difficult and limiting of the thickness of the lenticular sheet or lens array. For example, a traditional lenticular sheet may be provided with a lens frequency 62 LPI, and using standard printing methods, this provides a maximum printability of about 20 images per lens. In other words, the interlaced image could potentially include 20 images or frames of a movie such that 20 interlaces would be provided in each image or interlace set mapped to each lenticule or lens. A 62 LPI lens array results in each lens or lenticule having a width of about 16.7 mils such that the each of the 20 interlaces or image slices has a width of about 0.833 mils. Using standard printing methods, an interlace width of 0.833 mils is acceptable with printing thinner interlaces (such as down to around 0.5 mils) being much more difficult if not impractical.
There is, however, a growing demand for lenticular devices that can display interlaced images with a much greater number of images or information than standard printing methods can readily support. For example, there is significant demand for lenticular devices that can produce video or animation clips or imagery that is several seconds in length. Instead of 20 images or frames being provided in an interlaced image, these effects may require 30 to 50 or more images or frames. Building on the example of a 62 LPI lens array or lenticular sheet, it may be desirable to provide 58 images in an interlaced image, and using conventional interlacing or printing techniques, this would result in 58 interlaces in each image set being positioned under each lens. The lens is 16.7 mils wide so this results in an interlace width of about 0.28 mils for each interlace which is considered by many to be impossible or nearly impossible to image on plates or film (e.g., is much less than the 0.5 to 0.7 mils printing width believed by many in the industry to be a practical limit for printing interlaces) or at least impractical for most printing applications particularly a CMYK format in which all colors must register accurately in this small space or slice width. Additionally, the lens or lenticule likely will not focus this finely. Further, the data file required for the interlaced image would be very large (e.g., a size of 3,596 dots per inch (DPI)), which may create processing problems during creation of the image file and achieving proper mapping to the lenticular lens array.
Hence, there remains a need for lenticular devices or structures that provide an alternative to conventional lenticular lens arrays so that lens arrays or structures can be provided to view conventional interlaced images (e.g., images interlaced as for use with conventional lenticular material to achieve 3D, animation, or other visual effects) and advanced interlaced images (e.g., interlaced images with significantly greater number of images, frames, or information to create longer animation clips or animation or improved effects). Preferably, such lenticular devices would allow the lenticular sheet or lens array to be manufactured using relatively conventional techniques and also allow the interlaced image or ink layer to combined with the lenticular sheet inexpensively to produce high quality but affordable products such as cards, labels, and packaging that incorporate the lenticular devices.